The present invention relates to direct broadcast subscription television systems and apparatus. Specifically, an apparatus and method are provided for receiving and decoding various classes of scrambled subscription broadcasts.
Subscription television service has been authorized by the Federal Communications Commission wherein subscribers in a listening area may receive television programs providing that a subscription to the program is purchased by individual viewers from the program originator. Scrambling of the broadcast signals is provided during the transmission of the broadcast to prohibit unauthorized television receiving stations from viewing the program material. Various scrambling techniques have been proposed in the art for providing security to the originating program so that only authorized subscribers may view the program material.
Some of the earlier proposed systems for scrambling subscription broadcasts include the transmission of a subscriber identification number with each of the transmitted broadcasts so that decoding equipment at a subscriber's television receiver will recognize the presence of an identification number being transmitted, and will activate or deactivate descrambling means at the receiver for restoring or prohibiting the scrambled video and audio signals to be conditioned whereby a television receiver will properly display the program material.
The above scrambling technique has been proposed for use with television stations which provide a basic periodic subscription service whereby individual television receivers have descrambling equipment which are capable of comparing a machine readable identification number, supplied to the subscriber at the time the subscription is purchased, with an identification number transmitted by the station during broadcasting of the scrambled program.
The capability of subscription television broadcasts can be greatly enhanced with a provision at the subscriber's television receiver for distinguishing between special broadcasts, which carry programs having an additional purchase price associated therewith over and above the basic subscription price, from regular subscription broadcasts. Feature films, sporting events, and special adult entertainment can then be provided by the broadcaster in such a system at an additional premium one-time charge resulting in at least two tiers of programming.
The present invention is directed to providing a system for permitting special programming to be implemented in addition to the basic subscription programming previously purchased by a subscriber.